In general, an aluminum support to be incorporated in lithographic printing plate is required to exhibit excellent water wettability and water receptivity. Thus, it is well known that an aluminum support is finely roughened by a mechanical, chemical or electrochemical process so that it is grained. It is further known that the surface of the aluminum support thus grained is anodized to enhance the mechanical strength and even the water receptivity thereof. The aluminum support which has thus been anodized is then rinsed. During this procedure, aluminum ions contained in the anodizing solution and dissolved upon anodization are retained on the aluminum support. During rinsing, these aluminum ions form aluminum hydroxide which is then attached to the aluminum support to mar the external appearance. In order to eliminate this defect, it has been heretofore practiced to intensify rinsing. However, this approach is disadvantageous in that the required amount of rinsing water is increased, adding to the production cost.